Electric fuse.



C. W. DAVIS.

ELECTRIC FUSE.

APPLICATION FILED JUNE 18, 1913.

Patented Mar. 2, 1915.

2 SHEETS-SHEET 2.

E@ HCL ESSES'I' v l `.residing at,` Edgeworth, in the county of` UNTTEDsTATEs PATENTv oEEioE.

CHARLES W. DAVIS, 0F .EDGEVVOB'IH, PENNSYLVANIA, ASSIGNOR TO STANDARD.UNDERGROUND CABLE COMPANY, OF PITTSBURGH, PENNSYLVANIA, .A DORP()iRATION or PENNSYLVANIA.

ELECTRIC FUSE.

Specication of Letters Patent.

Patented Mar. 2, 1915.

' Application filed June 18, 1913. Serial No. 774,430.

To all whom it may concern:

l'Be it known that I, CHARLES W. DAVIS Allegheny and "Stat-e `ofPennsylyania, acitizen olf the United States, have invented ordiscovered certainnew and useful Improvements in ElectricFuses,'"offwhich .im-.

provement the following is a specification.

My invention relates to fuses adapted to be placed in electriccircuitsand to interrupt such circuits when Ithe current carried thereby reachesor exceeds a predetermined amount, and has to o particularlyT with whatare known as oil fuses for h'igh tension circuits, such fuses beingcharacterized by the use of a body of liquid, as oil, carbontetra-chlorid, etc., toJ dampen out or quench the arc formed upon theblowing of the fusible element. 1 l It is known that the blowing of afuse in a yhigh tension circuit is attended, particularly when suchblowing is caused by a short circuit, with the release of a greatamountof energy, whichA has the effect ofv a relatively powerfulexplosion. Even when a short fusible element is usedy in combinationwith means for lengthening the gap between tlie free ends of theconductor, the explosive forces, acting' against the relativelyAunyielding mass of liquid, may be of such intensity as to seriouslyinjure the fuse structure and endanger workmen in the vicinity thereof..provide an oil fuse construction whereby a large portion of the energyreleased upon the blowiiig of the fusible element may be consumed, thuseliminating to a large extent such prejudicial effects as have beendescribed above.

)In the accompanying drawings, which' itis the object of my presentinvention toV feired form I inclose the fusible element and theconductor leading theretoY within a cas.- ing, and I arrange therein aplurality of successive communicating chambers, some being filled, witha liquid and others with a compressible gas as air, such chambers beingso disposed that the expansive forces must exert their pressure throughthem, compressing the gas in the gas chambers and moving the liquid inthe liquid chambers. The chambers are arranged so that.

there will be a circuitous path of escape for the expansive forces,thereby adding to the energy-consuming function of the fuse' structure.In the preferred form of my invention, I also'p'rovide means forWidening j the gap between the free ends of the conductor after thefusible element has been destroyed; and, in the path of the movableconductor or conductors, I makesprovision for relatively thin layers ofliquid which readily becomes vaporized by the elongated are as the freeend of the conductor passes by or through such layers, thereby consuminga still further partof the ener y of the arc. And, in order Jto assistin reaking down the are, the partitions which' separate the vaporizablelayers of liquid are :preferably formed of a non-arcing metal.

Referring now to the embodiment of my invention illustrated in Figs. 1,2 and 3, and first to the general installation shown therein, the cables1 enter through the bottom of the junction box and are each providedwith suitable terminalI structures 3 which end in spring clips 4. Thefuse casing-5 is preferably cylindrical, open at both ends,I

and is carried b'yiyokes or brackets 6 of conducting material, providedat their lower en ds with knife blade contacts 7,- and secui-ed at their'upper ends to a suitable -handle 8. Extending between and eleetri callyconnected to the brackets 6 is a conductor consisting preferably offlexible end portions 9, relatively rigid portions'lO and a centralfusible element 11, the casing 5 infusible element 11.

closing the conductor portions 10 and' 11. The conductor portions 10 maybe provided with suitable abutments 21 which resist the current ofliquid as it escapes from the casing 5, and thus cause the conductors toreadily move outwardly, vwidening the gap between their free inner ends.In this embodiment of my invention a relatively large air or gas chamberis formed just above the liquid surrounding or adjacent to the fusibleelement by means of a supplementary cylindrical'casing 12, closed atitsupper end, and provided with suitable openings 13, through whichtheconductor portions 10 extend, and which a-Eord an outlet for theexpansive gases. At each side of the casing 12 a plurality of plates 14,preferably formed of non-arcing metal, depend fromr the upper wall ofthe casing 5 and formV between them chambers 15 and 16, adapted tocontain, respectively, relatively thin layers of liquid and gas. Betweenthe outermost plates 14 and the ends of the casing 5 a. plurality ofplates 17, 17a, 17b and 17c depend from the upper wall of the casing 5;and alternating with these plates there are a plurality of plates 18,18a and 18h extending upwardly from the bottom of the casing. rI`heliquid within the junction box 2 fills the entire lower portion of thecasing 5 submerging the conductor portions 10fthroughout then' fullextent, and preferably submergmg the It will be understood, however,that the fusible element may, if desired, be arranged immediately abovethe liquid. Such liquid also fills the chamber between the plates 17aand 17", there being air chambers or pockets formed between the plates17 and 17a, and 17b and 17. As will be readily seen, suitable holes 19are p rovided through the upper walls of the casing 5 in order to allowthe liquid of the junction box 2 to fill desired chambers between plates14C, and between plates 17a and 17". The edges of plates 17, etc., and18, etc., preferably extend beyond the .general center of the casing 5,and are each provided vwith a groove 20 so that the conductor may bereadily replaced when blown.

In operation, when the fusible element 11 blows, the gases, followingthe line of least i resistance, rst compress the air within the casing12, and `then exert their pressure throughthe circuitous passage formedby the successive liquid and gas chambers, compressing the gas in thegas chambers and moving the liquid in the adjoining liquidfilledchambers both in the upper and lower part ofthe casing. As the liquid isexpelled from the end of the casing 5 it strikes the Yaloutrnents 21 andcauses the conductors to move outwardly. However, when the explosiveforces are of extraordinary intensity, I find that their action inexpanding through the caslng 5 w1ll, without the assistance of theabutments 21, either expel the conductors from the casing or materiallywiden the gap between their free ends. As the arc 1s drawn out itvaporizes the relatively-thin layers ofliquid between the plates 14, and

ysuch plates are also effective, by dividing the are into small lengths,to break it down.

In Figs. 4 and 5 a second form of fuse casing is illustrated. In thisform, alternating gas and liquid containing chambers are provided by,means of a plurality of concentric cylinders, having holes through whichthe conductors 10a, 11a extend. The central cylinder 22 incloses a bodyof air immediately above the fusible element 11a, a tubular body ofliquid occupies the space between the cylinder 22 and 23; and airoccupies the space between the cylinders 23 and 24 above the conductorportions 10a. The handle S, only a portion ofy which is shown, issuitably secured to the top -of the casing formed by such cylinders. Itwill be understood that the structural elements shown in the fuse of Fig. 1 may also be used in this form to adapt it for service in aninstallation similar to that of Fig. 1. The operation of thissecond formof fuse will be readily apparent from the above description of theoperation of the fuse of Fig. 1. y

In the tests which I have made upon my improved fo'rm of electrical fuseI iind that a very substantial part of the energy released upon theblowing of the, fuse is consumed within the fuse casing, and thatcircults carrying currents of great strength may be interrupted quietlyand withoutA prejudicial' explosive effects. Also, I nd thattheinterruption of thecircuit takes place rapidly, in most instanceswithin the period of a half cycle of `the current which it carries.

I claim as my invention:

1. In an electric fuse installation, the combination with a fuse boXprovided with a body of arc-dampening liquid, and a pair of electricconductors lentering therein; of a fuse structure connecting saidconductors andy comprising a casing submerged in said liquid and havingan expulsion opening, a conductor within the casing provided with afusible element, land means for providing within saidv casing betweenits expulsion plates extending alternately from the top and bottom ofthe elongate casing and between said rst mentioned plates and the endsof the elongate casing andlforming compartments Within theelongate'ca'sing, a fluid passage through the upper Wall of alternatecompartments, and 4a fuse strip comprising a central low fusion portionWithin said supplementary casing and high fusion portions exteriorlythereof.

3. In an electric fuse installation, the combination of a junction box,electric cables entering therein, a fuse structure connecting the(conductors Aof said cables and comprising a casing, a conductor Withinsaid casing having a fusible element as a part thereof, a plurality ofadjoining compartments within said casing arranged successively adjacentto said conductor, a body of arcdampening liquid Within said junctionbox submerging said fuseecasing, and fluid passages through -the`upperwalls of alternate central portion thereof, a plurality 'of platesextending alternatelyfrom the top and bottom of said casing and formingcommunieating compartments therein, uid passages through the upper wallsof alternate compartments, and a body of arc-dampening iuid Within saidjunction box submerging said casing.

In: testimony whereof I have hereuntoset m hand.

y CHARLES W. DAVIS. Witnesses Y vDrunen HAMULTON. L. -McGhEm

